c# - 如何使用 linq 查询获取所有 child

Question

我需要所有 child 的列表。我将如何只获取子项。

这是我得到 child 的方法

//lets get the parents along with the childs
var parents = from p in context.post
              where p.isDeleted == false && p.userid == new Guid(UserID)
                   let relatedchilds = from c in context.post
                                       where c.id == p.id
                                       select c.id
                   select new
                   {
                        p.id,
                        p.userid,
                        relatedchilds
                   }

//now lets get only the childs in the previous query
var childs = from c in parents
              select new
              {
                   c.relatedchilds.   //This is where my problem is
              }

如何只获取一列中的相关子项？

Answer 1

由于 relatedchilds 已经是每个父级中的一个集合，它本身就是一个集合，您可以使用 SelectMany()将嵌套集合展平为 id 的平面集合:

var childs = parents.SelectMany( p => p.relatedchilds);

或者查询格式:

var childs = from p in parents
             from child in p.relatedchilds
             select child;